This invention relates to vehicle power systems and, more particularly, to solid state power controls.
Vehicles, such as aircraft, typically utilize one or more power distribution units to distribute power from a primary power source to various vehicle systems. The solid state power controls in a power distribution unit typically includes an electronic switch, such as a FET, and electronic circuitry that provides wiring protection. The FET and circuitry are often referred to as a solid state power controller (“SSPC”). The SSPC provides a circuit breaker function to protect downstream loads and has found widespread use because of its desirable status capability, reliability, and packaging density. A typical power distribution unit may include hundreds or thousands of SSPC's.
The electronic circuitry of the SSPC typically includes a microcontroller that uses power from the primary power source to control the FET. In one arrangement, a DC to DC converter converts the voltage from the primary power source to a lower voltage for the SSPC. Additional power stages may also be used to provide isolation on a per FET basis. The voltage conversion is not 100% efficient and results in a power loss in each stage of power conversion.
One disadvantage of a typical SSPC is that the microcontroller continually draws power from the converter and power source. This results in continuous power losses in the converters. In a power distribution unit that includes hundreds or thousands of SSPC's, the cumulative power losses represent a significant inefficiency. Further, the SSPC power usage may occupy significant amounts of the available power from the primary power source.
There is a need for a SSPC that uses less power and reduces power losses. This invention addresses those needs while avoiding the shortcomings and drawbacks of the prior art.